This exploratory project aims to evaluate engraftment and myogenic potential of donor pericytes delivered systemically to host skeletal muscles. The long-term goal is the development of cell-based therapy for combating muscle wasting. The search for means to reduce muscle wasting has been especially intensified in Duchenne muscular dystrophy, a genetic disorder where mutations in the dystrophin gene lead to progressive waste of striated muscles and early lethality. Muscle wasting is also associated with aging and is a hallmark of a number of diseases, including cancer, bacterial sepsis, AIDS and diabetes. Muscle wasting can cause generalized weakness and debilitation and in its extreme, when respiratory muscles are involved, asphyxia and even death. One of the proposed ways to treat muscle wasting disorders is engraftment of donor cells that can contribute to myofiber repair and increase muscle mass. The donor cells would need to be delivered effectively to multiple host muscles, preferentially via circulation. However, ongoing studies have shown that intra-venous delivery of donor cells is problematic because many of the cells are trapped in the lungs (and other filter organs). Thus, at present, intra-arterial cell injection seems to be the favorable means for efficient delivery of donor cells. Satellite cells, bona fide myogenic stem cells and their proliferating progeny are unable to reach target muscles when delivered systemically. Recent studies have pointed to the potential of perivascular cells for cell-based therapy in muscular dystrophy. The characterization of these atypical myogenic sources has been based on their properties following ex vivo expansion. The terms mesoangioblasts (endothelium related CD31+ cells) and pericytes (microvasculature- associated contractile cells that engulf the endothelium) have been used interchangeably without a clear resolution of their actual nature. In all, the functional significance of microvasculature sources of myogenic cells in cell-based muscle therapy has remained a subject of debate. In order to analyze the phenomenon in a reproducible manner, standardized approaches need to be developed for isolating and characterizing these atypical sources of myogenic cells. The specific aims of this application are: 1. Determine whether systemically delivered donor pericytes can target dystrophic muscles and be incorporated into myofibers. 2. Evaluate the potential of the engrafted donor cells to restore expression of proteins essential for muscle integrity. To address these specific aims we will first use dystrophin deficient (mdx) host mice and analyze pericyte effectiveness in restoring dystrophin expression in the sarcolemma. Donor pericytes will be delivered via the femoral artery. The anticipated outcome of the proposed studies will provide valuable insights for cell-based therapies in muscular dystrophies and other muscle wasting conditions. PUBLIC HEALTH RELEVANCE: Muscle wasting is associated with muscular dystrophies and causes generalized weakness and debilitation and in severe cases, leads to early lethality. Muscle wasting is also associated with aging and is a hallmark of a number of diseases including cancer and diabetes. The proposed study will evaluate whether systemically delivered donor cells can reach target muscles and contribute to muscle repair and increased muscle mass. The anticipated results will provide important insights for developing cell-based therapies to combat muscle wasting disorders.